The Effects of Weather The Effects of Weather on Aircrafton AircraftPart 1 of 2Part 1 of 2

Lesson OverviewLesson Overview

How ice impacts flightHow ice impacts flight How a microburst can induce wind shear on How a microburst can induce wind shear on

an aircraftan aircraft How sandstorms can be hazardous to air flightHow sandstorms can be hazardous to air flight How wake turbulence affects air flightHow wake turbulence affects air flight

How Ice Impacts FlightHow Ice Impacts Flight

13 January 198213 January 1982 Air Florida Flight 90 took Air Florida Flight 90 took

off from Washington DC off from Washington DC Reagan-NationalReagan-National

Snow was falling fastSnow was falling fast Plane was de-iced twice Plane was de-iced twice Plane waited on runway Plane waited on runway

59 minutes 59 minutes It crashed into 14It crashed into 14thth St St

bridge less than 2 miles bridge less than 2 miles north of runwaynorth of runway

74 passengers and 5 crew were on aboard74 passengers and 5 crew were on aboard The plane’s tail hit the bridge, breaking offThe plane’s tail hit the bridge, breaking off The nose pitched down, crossed the bridge and The nose pitched down, crossed the bridge and

plunged into the icy Potomac Riverplunged into the icy Potomac River A flight attendant and 4 other passengers survivedA flight attendant and 4 other passengers survived 4 motorists on the bridge were also killed4 motorists on the bridge were also killed

How Ice Impacts FlightHow Ice Impacts Flight

Air Florida Flight 90 -- Air Florida Flight 90 -- What Happened?What Happened?

Engine anti-ice system was not turned onEngine anti-ice system was not turned on System runs hot air over engine parts and keepsSystem runs hot air over engine parts and keeps

probes that monitor engine performance free of ice probes that monitor engine performance free of ice Engine thrust probe was iced overEngine thrust probe was iced over

Probe told pilots thrust was greater than it really wasProbe told pilots thrust was greater than it really was As a result, crew pitched nose up 30-40 degrees even as As a result, crew pitched nose up 30-40 degrees even as they they

were losing altitude just before hitting the bridgewere losing altitude just before hitting the bridge Crew took off even though snow and ice covered the Crew took off even though snow and ice covered the

airfoils (wings)airfoils (wings) Crew had little experience flying in snowy weatherCrew had little experience flying in snowy weather

Ice HazardsIce Hazards Ice affects lift, weight and dragIce affects lift, weight and drag Ice can also make hard to see out windshieldIce can also make hard to see out windshield

Lift

Weight

Thrust

Drag

Lift, Weight and DragLift, Weight and Drag

As ice builds up, lift is decreased while weight and As ice builds up, lift is decreased while weight and drag are increaseddrag are increased

Increasing angle of attack will cause boundary layer Increasing angle of attack will cause boundary layer of airflow to separate quicker leading to a stall of airflow to separate quicker leading to a stall condition earlier than normalcondition earlier than normal

Therefore, pilot must increase thrust to maintain liftTherefore, pilot must increase thrust to maintain lift

Causes of IcingCauses of Icing When supercooled water hits the airfoil, windshield, propeller, and When supercooled water hits the airfoil, windshield, propeller, and

other surfaces, part of the droplet freezes instantaneouslyother surfaces, part of the droplet freezes instantaneously How the remaining water droplet freezes determines the type of ice How the remaining water droplet freezes determines the type of ice

formationformation ClearClear RimeRime MixedMixed

Ice builds quickly as an airplane flies through the super-cooled rain Ice builds quickly as an airplane flies through the super-cooled rain droplets or cloud condensationdroplets or cloud condensation

Video Clip 5:25 – 9:20Video Clip 5:25 – 9:20

IcingIcingCloud Types of ConcernCloud Types of Concern

Stratus

IcingIcingCloud Types of ConcernCloud Types of Concern

Stratocumulus

IcingIcingCloud Types of ConcernCloud Types of Concern

Cumulus

Forms of IceForms of Ice Clear -- hard, smooth, solid

glossy, see-through

Rime -- brittle, frostlike, white,rough; easier to remove than clear ice

Mixed -- mixture of clear and rime; mushroom buildup on leading

edge

Icing – Preflight ActionsIcing – Preflight Actions

Check with weather forecastersCheck with weather forecasters Review and file your flight planReview and file your flight plan Storing aircraft in bad weatherStoring aircraft in bad weather De-Icing SolutionDe-Icing Solution Rule of Thumb – The only safe aircraft is a Rule of Thumb – The only safe aircraft is a

clean aircraftclean aircraft Video Clip (14:30 – 16:10)Video Clip (14:30 – 16:10)

Icing – In-Flight ActionsIcing – In-Flight Actions Anti-Icing EquipmentAnti-Icing Equipment

Pilot HeatPilot Heat Windshield HeatWindshield Heat Prop HeatProp Heat Inflatable “boots” for wingsInflatable “boots” for wings

Once icing is observed, the rate of accumulation and Once icing is observed, the rate of accumulation and how long you stay in those conditions become criticalhow long you stay in those conditions become critical

You must act => Climb, Descend, DivertYou must act => Climb, Descend, Divert You must first contact the ATC!! You must first contact the ATC!! Rule of Thumb – There is no such thing as a “little” iceRule of Thumb – There is no such thing as a “little” ice Video Clip (19:15 – 21:12)Video Clip (19:15 – 21:12)

Icing – ScenarioIcing – Scenario

You are flying at 5,000 feet through thick stratocumulus You are flying at 5,000 feet through thick stratocumulus You are halfway into a 4-hour flightYou are halfway into a 4-hour flight You notice ice forming on your wingsYou notice ice forming on your wings Your engine is slowly losing power and running a little rougher Your engine is slowly losing power and running a little rougher

than normalthan normal What do you do?What do you do?

What if the ATC does not allow you to climb due to another What if the ATC does not allow you to climb due to another aircraft coming your way?aircraft coming your way?

What if the ATC does not respond?What if the ATC does not respond?

Video Clip (21:12 – 22:54)Video Clip (21:12 – 22:54)

Activity 1: Icing Activity 1: Icing Research TunnelResearch Tunnel

Watch the video “NASA at 50: Icing Watch the video “NASA at 50: Icing Research Tunnel Designated as Historic Research Tunnel Designated as Historic Landmark” Landmark”

Answer the analysis questionsAnswer the analysis questions

Chapter 2, Lesson 5